**2. Biogas production**

Biogas is a gas with 50-70% of methane (CH4) and 50-30% of carbon dioxide (CO2) content produced by the anaerobic decomposition of organic matter. It can be produced from a wide variety of available waste organic materials, including sewage sludge, animal manure, municipal/industrial organic waste, parts from ethanol production, crop residues, specially grown energy crops and more. Methane, the combustible component of biogas, mainly determines the properties of biogas. A m3 of biogas produced from food industrial organic wastes has on average a methane content of about 55% and therefore a calorific value of about 6.5 kWh (Angelidaki et al., 2003). Nowadays, the world markets for biogas are

potatoes, wheat, followed by distillation and drying. The production of bioethanol from corn or sugarcane is a mature technology. For example, in Brazil there are 448 bioethanol production units installed and according to a report of the Brazilian Ministry of Mines and Energy, ethanol production was 25 billion liters in 2008 (Soccol et al., 2010). Biogas is produced by anaerobic digestion of organic materials by anaerobic microorganisms. It can be used to produce thermal energy (heating), electricity, or if compressed – it can be used in vehicles. The current operation of biogas plants is relatively large in Europe, especially in Germany. According to Pöschl et al. (2010), the estimated biogas production potential in Germany is 417 PJ per year and 80% of which derived from agricultural resources, including farm waste (96.5 PJ per year), crop residues (13.7 PJ per year), and dedicated energy crops

More recently, hydrogen is playing more important role as a fuel used for heating, lighting and as a motor fuel. The main advantage of hydrogen as a future alternative energy carrier is the absence of polluting emissions when combusted, results in pure water. Today, most hydrogen gas is obtained from fossil fuels which generate greenhouse gas (GHG) that contribute to global warming. The biological hydrogen production is an attractive method because it can be produced from renewable raw materials such as organic wastes. Wastewater from food processing industries show great potential for economical production of hydrogen (Van Ginkel et al., 2005), but today no strategies for industrial-scale

The ability to produce biofuels from low-cost biomass such as agricultural waste and byproducts (including for example crop residues, sugar cane waste, wood, grass and wastewater from food processing industries) will be the key to making them competitive with other fuels, for example gasoline. Only biofuels derived from waste products show low environmental effects, such as reduction of GHG emission, small land demand and damage the environment. As a result, since UF whey permeate disposal represent a real problem for the dairy industry, biofuels production offers an ideal alternative to its valorization (de

The objectives of this work were to study the applicability of fermentation processes for the production of biogas (methane), fuel bioethanol and biohydrogen in Upflow Anaerobic Sludge Blanket (UASB) reactors fed with raw UF whey permeate. To optimize and enhance the biofuels production, the different processes were used (ultrasonic stimulation of microbial cells, anaerobic steel corrosion process) and the different operational parameters (pH, hydraulic retention times - HRTs regimes, organic loading rates - OLRs) were applied.

Biogas is a gas with 50-70% of methane (CH4) and 50-30% of carbon dioxide (CO2) content produced by the anaerobic decomposition of organic matter. It can be produced from a wide variety of available waste organic materials, including sewage sludge, animal manure, municipal/industrial organic waste, parts from ethanol production, crop residues, specially grown energy crops and more. Methane, the combustible component of biogas, mainly determines the properties of biogas. A m3 of biogas produced from food industrial organic wastes has on average a methane content of about 55% and therefore a calorific value of about 6.5 kWh (Angelidaki et al., 2003). Nowadays, the world markets for biogas are

(236 PJ per year).

productions have been found.

Glutz, 2009; Silveira et al., 2005).

**2. Biogas production** 

booming. Advances in biotechnology, molecular science and microbiology contributed to enhancements in biogas yields production (more high tech resulting in over 70% plant efficiency), which led to the development of commercial biogas plants (Yadvika et al., 2004). As a result, biogas competes with petroleum-based fuels in terms of performance, cost, and additional benefits such as reducing GHG emissions. Currently Europe dominates in biogas production (Prochnow et al., 2009). Germany, the biogas market leader, runs about 5000 biogas plants in 2009, covering more than 1% of the electrical energy consumption from biogas (Meyer-Aurich et al., 2012). However, the trend in producing biogas is also catching up fast in countries like Japan, Australia, New Zealand, USA, China and India.

Innovations are still necessary to support research and development in the field of renewable energy. The main research area is closely related to renewable biomass feedstock. Consequently, the objectives of this work were: (1) to investigate anaerobic biogas potential from UF whey permeate, (2) to evaluate if steel elements could enhance the performance of UASB reactors treating UF whey permeate (COD removal efficiency, phosphorus removal), and (3) to study the influence of steel elements on the biogas production rate and methane content in biogas.
